go to https://www.openstreetmap.org/ and enter “Moreton View Tower and Villas” into the address search bar. It will take you to this building on the map.

Press the “Edit” button at the top of the screen and follow the instructions.

If you don’t want to do all that for some reason you can also use the button to the right of the map to add a note to the map. Please explain what needs to be changed and why and some friendly mapper will take care of it.

@hfs Thanks for your answer. I have updated correct postalcode for the above address. But when call reverse geocoding of that location, got that incorrect postalcode only. So how to update postal code for a region on map?